How Big is Too Big (When it Comes to Smartphones)?

I've long maintained that any phone with a screen size over 4.2 inches is stupid and pointless, and then promptly went out and got an iPhone 6. It seems, though, that everyone's acceptance of what the maximum screen size is varies pretty massively.

Personally, I fall into the category of 'people with tiny hands', so I've always been a fan of smaller phones; they're easier to hold, and I don't actually find bigger screens that much better. Plus, I use a dinky little tablet for all that video watching/book reading, so my phone mostly does phone things like sending messages or calling cabs or ordering pizza.

But I'm entirely aware that Apple's R&D team caters to more than just the 20-something-tech-journalist-with-entertainingly-small-hands demographic, so I get that there might be good reasons for phones to be bigger. I just haven't heard them yet.

So, let's settle this once and for all. What do you think is the perfect size for a smartphone? Answers, justifications, and hand size below, please.